U.S. Magistrate Judge Arthur Boylan said Taya Kyle, who has been appointed executor of her husband's estate, would be a proper substitute in the case and requests to substitute defendants are freely granted.

Ventura claims Chris Kyle defamed him to gain notoriety for his best-selling book, "American Sniper." In it, Kyle describes a 2006 bar fight in which he claims he punched someone named "Scruff Face," whom he later identified as Ventura.

Ventura claims the fight never happened.

An attorney for Ventura had argued that Taya Kyle should be substituted as a defendant because Chris Kyle's estate will continue to profit from book sales and a recent movie deal, and Ventura has a right to protect his reputation.

Taya Kyle's attorney had argued Ventura would be better off dropping the case, saying that going forward would give the perception that Ventura had little regard for loved ones of deceased war heroes.

Kyle is considered to be the deadliest sniper in U.S. military history. He was killed in February along with his friend Chad Littlefield at a Texas gun range. Iraq War veteran Eddie Ray Routh has been charged in their deaths.